Clutch or brake employing magnetic particles



Aug. 10, 1954 E. R. VOTRIAN 2,685,947

CLUTCH 0R BRAKE EMPLOYING MAGNETIC PARTICLES Filed June 17. 1950 2 Sheets-Sheet 1 2 INVENTOR.

ELMER R.VOTR|AN ATTORNEY Aug. 10, 1954 E. R. VOTRIAN 2,635,947

CLUTCH OR BRAKE EMPLOYING MAGNETIC PARTICLES Filed June 17, 1950 2 Sheets-Sheet 2 IN V EN TOR.

ELM ER R. VOTRIAN Y A MK M ATTORNEY Patented Aug. 10, 1954 CLUTCH- OR BRAKE EMPLOYING MAGNETIC PARTICLES Elmer R. Votrian, Fallon,=Ill., assignor to Vick- .ers'lncorporated,Detroit, Mich, a corporation ot'Michigan Application June 17, 1950, SerialNo. 168,787

2 Claims. 1

Thi invention relates to magnetic coupling devices.

Magnetic couplingdevices, such as-clutches, brakes, etc. -employing magnetic particles to transmit torque between spaced coupling members may, with respect to-the magnetic working gapconfiguratiom'be divided into two general categories. In one type, the magnetic working gaps are cylindrical or radial and are formed by concentric magnetic cylinders, whereas in the second'type the gaps are axial and are formed by sandwiched multiple discs, the spaces therebetween being the gaps.

As in other rotating machinery, therotating parts of magneticcoupling devices should be dynamically balanced in order to reduce vibration during operation. -To achieve reasonable balance, any integral rotating part formed from a plurality of components secured together should be balanced as an integral unit, and not in any divided form. Heretofore, this has not been generally possible in the case of multiplev disc magnetic coupling devices. This is due to thefact that the alternate discs must beassembled piece by piece before each of the integral relatively rotatable memberscan be clamped together as a rotatable unit.

The invention herein contemplates a magnetic V of relatively rotatablecoupling members, a drivcoupling device having a plurality of c upling discs wherein alternating discs have complementary teeth and slots therebetween which permit axial assembly of integral units instead of the heretoforepreferred to piece by piece assembly.

It is thereforeanobject to provide a new and useful magneticcoupling device.

Further objects and advantages of the present invention will be apparent from the following ing member It and a driven member 12 both having a plurality of magnetic surfaces defining a plurality of magnetic working gaps It partially filled with particles of magnetic materials l5, such as iron, which may be mixed with either a wet or dryv lubricant.

The driving member it iskeyed to a shaft I3 and includes a magnetic yoke [9 made from a pair or" toothed circular pole sides 29 and 22 surrounding the shaft-lE, and abutting each other as indicated at 24 to form a low reluctance joint and an annular channel-25 with a U -shaped crosssection for receiving a magnetizing coil 28. Leads and 32 from the coil 28 are brought out through a small opening 34 at the joint 24 and an axial slot 36 in the shaft l8, and are connected to a pair of slip rings 38 and it] carried by an insulating disc 42 fixed on a collar 43 to rotate with the shaft l8. Apair of brushes id and 45, contacting the rings 38 and it, respectively, may be connected to a suitable source 48 of control currentthrougha variable control at. The path of control current to the exciting coil 28 is obvious from the figure.

The pole sides 29 and 22 are circumferentially slotted to provide'teeth'iii and 54, respectively, which extend radially. outward from intermediate portions of the respective pole sides. Clamped between the pole sidesZii and 22 are a plurality of toothedmagnetic plates or discs 56 separated by non-magnetic Spacer rings The teeth ti on these circular plates or discs also extend radi" ally outward.

The discs are spacially interleaved between magnetic ring-like discs 52 of the driven member description, reference being had to the accom .panying drawings wherein a preferred form of v the present invention-is clearly shown.

In the drawings:

Figure 1 is a sectional viewillustrating amag- 7 {2 which have radial inwardly extending teeth at and are carried by two non-magnetic end hells taiand .iii between which the discs spaced non-magnetic rings are clamped... The spaces betweerithemagnetic discs $2 and the magnetic discs 55 and the pole sides 25 and 22, defined by adjacent-fiurfacesoidiscs 62 and 5t and adjacent surfaces ofdiscs-fiz and pole sides is and 22, arethe magnetic-Working gaps M of the clutch and-are filled tora suitable extent, with magnetic t 7 particles l5, either aione-ormixed with a lubricant or any other desired material.

Heat dissipation is materially aided by the large area of the discs 62 whose outer portions act as cooling'fins.

The driven member l2, which includes the end bells 58 and 68 and the magnetic discs 62 carried thereby, completely encloses the driving member Ill, and is journalled for rotation about shaft IS on bearings 12 and M which are mounted on sleeves l6 and 18 disposed on opposite sides of the driving member and fitted on the shaft 18. As seen in Figure 1, axial rigidity and desired spacing is maintained by clamping in series and in the following order the collar d3, sleeve 16, the magnetic yoke l9, and sleeve 19, between an annular shoulder 89 formed on the shaft 18, and a washer 82 drawn up to the shaft by a machine screw 84.

Leakage of magnetic particles into and through the bearings '52 and M is prevented by seals 89 and 38 carried by bearing retaining rings 99 and 92, respectively, which are secured to the inner sides of the end bells 66 and 59. The output of the clutch is taken through a shaft {is connected to a flanged coupling 96 secured to the end bell 68.

The teeth on the discs the discs 92, and the pole sides 26 are so proportioned and spaced that the teeth on the discs of the driving member ill will axially pass through the interdental spaces (slots) of the discs of the driven member and vice versa; that is, the teeth on the discs of either member will pass through the interdental spaces on the discs of the other member upon relative axial movement between the members such as would occur if it were desired to disassemble the clutch by first removing the end bell es of the driven member l2 and then pulling out the driving member i9 intact.

The teeth of the discs on both members may be align d in any suitable manner which will permit axial passage of one member through the other so that the inner member may be dynamically tested as a unit, the clutch assembled without the necessity of removing the separate discs of the inner member. Two variants of tooth alignment are shown in Figures 3 and l. In Figure 3, the discs in each member are aligned so that their teeth are in straight rows across the discs, whereas in Figure i the discs in each member are aligned so that a stag-- gering effect is obtained. In assembling or disassembling the embodiment illustrated in Figure 4, the members are axially moved at a distance of about one disc at a time, then partially turned and axially moved again, etc.

Thus it will be seen that the inner member Iii can be assembled intact into the clutch, and that the inner member will be accessible as an integral unit for balancing purposes. The outer member 12 is, of course, externally accessible for balancing. It will be appreciated that although 1e inner member is the driving member and the outer member is the driven member in this disclosure, their relative position may be reversed; that is, the inner member may be the driven member, etc. The invention is equally applicable where the one coupling member is fixed and the other coupling member rotates as in a magnetic brake. In any case, the coupling members are referred to as relatively rotatable, whether one or both are rotatable, and whether slipping, lockin, or other type of action is required.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A magnetic particle coupling device comprising relatively rotatable inner and outer coaxial magnetic coupling members, the outer memher having radial teeth extending inwardly to define a circular opening, the inner member having radial teeth extending outwardly, said teeth having broad surfaces in planes perpendicular to the axis of said members, the teeth of one member being interleaved between teeth of the other member whereby broad surfaces of the teeth of the respective members face each other in axially spaced apart relation to define a plurality of axially spaced working gaps in substantially parallel planes, magnetic particles in said gaps, and magnetizing means for exciting said particles thereby to form a force transmitting bond between the teeth of the respective members, said teeth being so proportioned and spaced that the teeth of one member can pass through interdental spaces of the other member upon relative axial movement between said members.

2. A magnetic particle coupling device comprising relatively rotatable inner and outer magnetic coupling members the inner member having a plurality of discs each having outwardly extending teeth around its periphery, the outer coupling member having a plurality of ringshaped discs each having inwardly extending teeth around its inner circumference, all of said teeth having broad surfaces in the planes of their respective discs, the discs of both members being interleaved and spaced whereby teeth of the respective members are axially spaced apart but overlap radially, magnetic particles in the spaces between the discs of the respective members, and magnetizing means for exciting said magnetic particles thereby to form a force transmitting bond between the respective coupling members, the proportions of said teeth and the interdental spaces being such that upon relative axial movement between the inner and outer embers the teeth on the discs of one member can pass through the interdental spaces of the discs of the other member.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,192,233 Severy July 25, 1916 1,666,445 Last Apr. 17, 1928 1,901,988 Rudquist Mar. 21, 1933 2,002,629 Cobb et a1. May 28, 1935 2,510,675 Baruch June 6, 1950 2,629,472 Sterner Feb. 24, 1953 FOREIGN PATENTS Number Country Date 485,591 Belgium Nov. 13, 1948 671,684 France Dec. 16, 1929 OTHER REFERENCES Magnetic Fluid Clutch in Servo Applications, Nov. 19, 1949, Electronics, pages to 103, inelusive. 

